The present invention relates to a semiconductor device and a method of manufacturing a semiconductor device and can be suitably used for, for example, a semiconductor device using nitride semiconductor.
GaN nitride semiconductor has high electron mobility and a wider band gap as compared with Si and GaAs, so that it is expected to be applied to a transistor for use of higher withstand voltage, higher output, and higher frequency. In recent years, the GaN nitride semiconductor is actively developed. Among such transistors, a transistor having a normally off characteristic is useful, and a structure for providing the normally off characteristic is examined.
For example, Japanese Unexamined Patent Application Publication No. 2013-065649) discloses a transistor using a nitride semiconductor layer as a channel. In the transistor, 2DEG (two-dimensional electron gas) is generated at an interface between a barrier layer and a channel layer. Below the gate electrode, a cap layer is provided, and generation of 2DEG is suppressed.